This invention relates to a water supply system and is particularly useful in conjunction with agricultural irrigation units.
A basic problem with mobile agricultural irrigation units is supplying the moving sprinkler pipe with water. One well known solution is to have one end of an irrigation system fixed while the rest of the pipe rotates about that point. Water is then supplied to the pivot point. These so-called center-pivot systems are inefficient in that they fail to irrigate the corners of the square circumscribed about their circular path. This problem can be avoided by use of a system which moves laterally to the length of the sprinkler pipe. The so-called lateral move systems conform nicely to the shape of most agricultural fields but present a problem of supplying them with water.
Various schemes have been devised to meet this difficulty. Among these are: an open channel or ditch running perpendicular to the sprinkler pipe; a closed supply pipe with valves or spigots located at intervals; providing a flexible supply hose which is paid out or reeled in as necessary to connect the sprinkler pipe to a water source. These all have disadvantages of one sort or another. The open channels can be used only on very flat ground. The spaced valve arrangement requires either periodic inputs of manual labor or complex valve changing apparatus, thus making it less suitable for automatic operation. The flexible hose arrangement is feasible only for small fields as the weight and size of the hose and reel combination becomes prohibitive for larger fields.
There have been attempts to solve the problem by providing a pipe which opens along a seam for feeding into a moving pipe. See Boone U.S. Pat. No. 3,268,174 and Reinke U.S. Pat. No. 3,592,220. These arrangements have the difficulty of requiring a seal, between the moving pipe and supply pipe, which extends along the entire length of the supply pipe. Also, they permit only a minimal flow because the sealing arrangement between the moving pipe and the stationary pipe allows only a very small opening. This limitation is caused by the fact that some element of the moving pipe must penetrate the primary seal means to provide fluid communication between the stationary pipe and the conduit connected to the moving pipe.